Dispensers are a convenient way for providing fluid from a remote underground reservoir to a number of fluid containers. In particular, fuel dispensers provide fuel to transportation vehicles from an underground storage reservoir. In order to refuel the vehicle, the vehicle must be parked in close proximity to the fuel dispenser. This may result in the fuel dispenser being accidentally knocked over or hit by the vehicle.
For such cases, current fuel dispenser designs include an impact valve that close off the fuel flow from the fuel reservoir to the internal dispenser hydraulic plumbing. This impact valve prevents mass fuel flow from spilling onto the ground floor and allows an operator enough time to shut off the fuel delivery pump. But it should be noted that impact valves generally fail to completely seal the internal dispenser hydraulic plumbing from the underground piping system when the system is pressure tested for leaks.
Government regulations mandate periodic checks of the underground piping system for leaks, thereby requiring that the fuel dispensers be isolated. One method of isolation of the fuel dispenser includes the closure of the impact/emergency valve to isolate each fuel dispenser from the underground piping system. This method is inadequate because the pressure from the fuel delivery pump causes leaks to occur past the impact valves.
Another method requires that the fuel delivery pump be shut off, so that the internal dispenser hydraulic plumbing can be disconnected from the underground reservoir. The fuel dispenser is then tipped so that the conduit leading to the underground piping system can be capped off. This method may result in damage to the dispenser as well as being costly, time consuming and awkward.